Flexible, multilayered transfer tape

ABSTRACT

A flexible, multilayered transfer tape is described which contains an auxiliary support, a layer of pressure-sensitive adhesive and a binder containing a white-pigmented transfer layer having greater adhesion to the pressure-sensitive adhesive layer than to the auxiliary support. The transfer layer, which contains a binder in addition to a white pigment, is present between the auxiliary support and the pressure-sensitive adhesive layer. The transfer tape is characterized in that a non-white pigment is present in finely dispersed form in either or both of a polymer-bonded interlayer and the pressure-sensitive adhesive layer. The polymer-bonded interlayer may be situated between the white-pigmented transfer layer and the pressure-sensitive adhesive layer or in the white-pigmented transfer layer itself. Such transfer tapes have significantly improved covering capacity as compared to transfer tapes in which only the white-pigmented transfer layer is tinted.

FIELD OF THE INVENTION

This invention relates to a multilayer flexible transfer tape comprisingan auxiliary support and a layer of pressure-sensitive adhesive, abinder-containing white-pigmented transfer layer showing greateradhesion to the layer of pressure-sensitive adhesive than to theauxiliary support being present between the auxiliary support and thelayer of pressure-sensitive adhesive, and to the use of this transfertape in roll form in a hand-held dispenser.

BACKGROUND OF THE INVENTION

A transfer tape of the above-mentioned type is described in EP-A-0 318804. According to this document, it is preferably used in roll form in ahand-held dispenser to enable the transfer layer to be applied simply,quickly and uniformly to a substrate for covering errors in texts ordrawings and for making subsequent corrections. The transfer layer thusapplied may then be written on, for example with writing ink or Indiaink.

In the case of the described transfer tape, it is of advantage for thewhite-pigmented transfer layer to be darkened by the incorporation ofblack pigments, more particularly carbon black. The covering power ofthe transfer layer is improved in this way. However, the degree ofdarkening is limited insofar as, if the amount of black pigment used istoo large, the white appearance of the tape is impaired and can nolonger be described as white. Overall, this,solution is notsatisfactory.

BRIEF SUMMARY OF THE INVENTION

Accordingly, the problem addressed by the present invention was tofurther develop the transfer tape mentioned at the beginning in such away that the covering power of the transfer layer for the application inquestion would be improved without any serious effect on its“whiteness”.

According to the invention, the solution to this problem ischaracterized in that a non-white pigment is present in finely dispersedform

a) in a polymer-bonded interlayer situated

a1) between the white-pigmented transfer layer and the layer ofpressure-sensitive adhesive or

a2) in the white-pigmented transfer layer, and/or

b) in the layer of pressure-sensitive adhesive.

Overall, there are thus three versions of the multilayer flexibletransfer tape according to the invention. The version in which thenon-white pigment is finely dispersed in the layer b) ofpressure-sensitive adhesive is preferred. If, in individual cases, thedarker impression created when looking down onto the layer ofpressure-sensitive adhesive is undesirable, particularly when thenon-white pigment is a black pigment, such as carbon black, it is ofadvantage to use one of the two variants of version a).

BRIEF DESCRIPTION OF THE DRAWINGS

The three versions of the transfer tape according to the invention aredescribed in more detail in the following with reference to theaccompanying drawings.

FIG. 1 shows a known transfer tape comprising an auxiliary support (1),a transfer layer (2) and a layer (3) of pressure-sensitive adhesive.

FIG. 2 shows version a1) of the transfer tape according to theinvention. A polymer-bonded interlayer (4) containing a finely dispersednon-white pigment is present between the white-pigmented transfer layer(2) and the layer (3) of pressure-sensitive adhesive.

FIG. 3 shows version a2) of the transfer tape according to theinvention, in which the non-white-pigmented polymer-bonded interlayer is“sandwiched” by the white-pigmented transfer layer, i.e. thenon-white-pigmented interlayer (4) is present between the transfer layer(2) and an additional layer (2A) with the identical composition. Thefunction of the additional layer (2A) is to conceal the dark colorimpression created by the interlayer (4) when looking down onto atransparent layer of pressure-sensitive adhesive.

FIG. 4 shows version b) of the transfer tape according to the inventionin which a non-white pigment is finely dispersed in the layer (3A) ofpressure-sensitive adhesive.

DETAILED DESCRIPTION OF THE INVENTION

A “non-white pigment” in the context of the invention is preferably apigment which is substantially similar to the symbols, more particularlyletters, to be covered. These are normally blue, black, red or green incolor. In general, therefore, the color yellow should not be used. Blackpigments, especially carbon black, are particularly preferred inpractical applications. Basically, the particle size of the pigments isnot critical, although a particle size of about 1.5 to 0.005 μm and,more particularly, of less than about 1 μm to colloidal particle size ispreferred. Fine-particle metal powders, more particularly fine-particlealuminium, may be used instead of colored pigments. The aluminiumparticles are preferably lamellar and have a thickness of preferablyabout 3 to 10 μm. They may be up to about 15 μm in length without anyproblems. Water-based aluminium pastes have proved to be particularlysuitable. Aluminium pastes such as these are produced by a special wetgrinding process. A particularly preferred paste is marketed by CarlSchlenk AG under the name Aquasilber Aluminiumpaste LPW/1380.

The interlayer and/or the pressure-sensitive adhesive layer preferablycontain(s) at least about 0.1% by weight of non-white pigment, morepreferably about 0.1 to 5% by weight and most preferably about 0.2 to3.5% by weight of non-white pigment. If the quantity of non-whitepigments used in both layers is below the limit of “less than 0.1% byweight”, the desired effect cannot be obtained to the required extent.If, however, this quantity exceeds 5% by weight, no significantimprovement is obtained. If this limit is exceeded, for example inconnection with the layer of pressure-sensitive adhesive, the result mayeven be that the adhesiveness of this layer is adversely affected. Inorder to satisfy functional requirements, a quantity of about 3.5%should not be exceeded.

The transfer layer is “white-pigmented”. In other words, it containsconventional white pigments in the quantity necessary to provide thetransfer layer with a certain covering power. White pigments of the typein question include in particular titanium dioxide (titanium white) andprecipitated chalk, alumina and/or colloidal silicas. According to theinvention, however, there is nothing to prevent the transfer layer beingadditionally toned down with suitable, differently colored pigments.This can be done by incorporating suitable quantities of black pigment,more particularly carbon black, and also by toning down with otherpigments, for example yellow and green. Toning down may be necessarywhere the transfer layer is to be adapted to the color of the substrateon which the lettering, etc. is to be covered. The observations on theparticle size of the “non-white pigments” again apply.

Thermoplastic or thermoelastic polymers are used in the form of anaqueous solution or aqueous dispersion to form the binder-containingtransfer layer. The following substances are used with advantage tosolve the problem addressed by the invention:

a) polyurethanes with a molecular weight of 15,000 to 50,000, forexample Permuthane U 4924, a product of Stahl-Chemie, or Desmolac 2100,a product of Bayer AG,

b) linear saturated polyesters with a molecular weight of 20,000 to30,000, for example Vitel PE 307, a product of Goodyear Tire & Rubber,Polyflex 46962, a product of Morton,

c) styrene/isoprene/styrene copolymers, for example Clariflex TR 1107, aproduct of Shell-Chemie,

d) acrylates and methacrylates, for example Plexigum 7 H, a product ofRoehm, GmbH,

e) polyamides modified with diphenyl acid, for example Scope 30, aproduct of Rhône-Poulenc or Emerez 1533, a product of Emery Chemicals,

f) polymer dispersions based on vinyl propionate, for example Propiofan6D, a product of BASF, and

g) water-soluble carboxyfunctional polymethacrylate, for example RohagitSD15, a product of Roehm GmbH.

This list is by no means complete and does not represent any limitationof choice. On the contrary, it is quite clear to the expert that otherbinders may also be used, especially since the essence of the inventiondoes not lie in the type of binder used.

In order further to optimize the invention, the type of plasticizer usedshould also be taken into account in choosing the particular binder forforming the transfer layer. When the transfer layer is applied to thesurface to be corrected or covered, the plasticizer should not penetratethrough the normally thin layer of pressure-sensitive adhesive and comeinto contact with the text/symbols to be corrected or the pigmentspresent there, which would result in unwanted coloring of the transferlayer. Conventional plasticizers, such as silicone oil, castor oil andmineral oils, are suitable for this purpose. Plasticizers preferablyused in other fields of application, for example phthalic acid esters oroleic alcohol, are not as suitable. In order to counteract theabove-mentioned unwanted effect of plasticizers in borderline cases, aso-called “laking agent” may be incorporated in the binder-containingtransfer layer to precipitate or render insoluble any migrating pigmentsin order to prevent them from migrating into and thus coloring thetransfer layer applied. Suitable laking agents are tannin and tanninderivatives. The laking agents present in inks and India inks maygenerally be used. They should be present in the binder-containingtransfer layer in quantities of preferably about 0.5 to 5% by weightand, more preferably, about 1.5 to 3.5% by weight, the range from about2 to to 2.5% by weight being most particularly preferred.

To form the transfer layer, the particular binder selected is preferablypresent in the form of an aqueous solution or dispersion. In addition,the additives discussed in the following are optionally added. Thechoice of a suitable solvent or dispersant will be determined by thetype of binder used. Suitable solvents/dispersants include in particularlow-boiling to medium-boiling organic solvents from the group ofalcohols, such as ethanol, isopropanol and butanol, ketones, such asacetone and methyl ethyl ketone, esters, such as methyl and ethylacetate, aromatic hydrocarbons such as toluene, aliphatic hydrocarbons,such as spirit with a boiling point of 70 to 140° C., either on theirown or in admixture, and more particularly water either on its own or inthe form of a mixture with low-boiling, water-soluble organic solvents.

The concentration of the binder in the solution or dispersion is notcritical to the invention. As an approximate guideline, it should bebetween about 3 and 15% by weight and preferably between about 6 and 12%by weight. To form the transfer layer, the solution or dispersion isapplied to the auxiliary support in a quantity of preferably about 15 to25 g/m² (dry weight) and, more preferably, about 18 to 22 g/m².

An advantageous component of the binder-containing transfer layer is a“stripping aid”. When the transfer layer is applied to a substrate underconditions of tensile stress, the stripping aid ensures clean stripping.Suitable stripping aids are cellulose derivatives, among which thecellulose ethers soluble in organic solvents and/or water, such asmethyl, ethyl, hydroxyethyl, ethylhydroxyethyl and carboxymethylcelluloses, cellulose esters, such as cellulose acetobutyrate andpropionate, are particularly preferred. Many other soluble cellulosederivatives which produce the required effects are also suitable. Thebasic cellulose skeleton in the soluble cellulose derivative is clearlyimportant whereas the groups introduced by the cellulose modificationmerely lead to an increase in solubility in the selected solvent.

For optimal formation of the transfer layer, the quantity ratio ofstripping aid to binder is about 1:2 to 1:20 and preferably in the rangefrom about 1:4 to 1:10.

The layer of pressure-sensitive adhesive may consist of commercialpressure-sensitive adhesives. These are elastic and permanently tackyself-adhesive compositions with strong adhesion forces which adhereinstantly to various surfaces at room temperature, even under lightpressure. They are preferably applied in the form of an aqueousdispersion to the transfer layer and, optionally, interlayer alreadypresent on the auxiliary support because the layers already formed arenot redissolved in this way. Pressure-sensitive adhesives of this typeare, in particular, acrylate-based pressure-sensitive adhesives. Thesestarting materials may be viscous solutions and dispersions which arebased on rubber, polyacrylates, polyvinyl ethers or polyvinylisobutylene. Commercial materials based on polyacrylates are preferred.Suitable commercial products are Ucecryl 913 and Ucecryl PC 80 (marketedby ucb Dogenbos, Belgium) and polymer dispersion VP 959/6 (marketed byFreihoff). The pressure-sensitive adhesive to be applied, which isinitially present in an aqueous medium, preferably contains wettingagents or surfactants (marketed under the name Byk W). In version b) ofthe invention, a non-white pigment is finely dispersed in the solutionor dispersion of the pressure-sensitive adhesive to be applied. To formthe layer of pressure-sensitive adhesive, the dispersion/solution of thepressure-sensitive adhesive, optionally with additives, is applied tothe transfer layer or additional layer in a quantity of preferably about1 to 5 g/m² (dry weight) and, more preferably, about 2 to 4 g/m².

According to the invention, the layer of pressure-sensitive adhesive ispreferably about 1 to 5 μm thick and, more preferably, about 2 to 4 μmthick. The same range applies to the above-mentioned polymer-bondedinterlayer of version a). The white-pigmented transfer layer ispreferably 15 to 25 μm thick and more preferably about 18 to 22 μmthick. If the transfer layer were to be any thinner, productiondifficulties would arise or the functionality of the particular layerwould be affected. If the transfer layer were to be any thicker, nosignificant improvement would be obtained and unnecessary costs would beincurred. Also, a relatively thick tape cannot be used with the sameadvantage in a hand-held dispenser because, if the tape were too thick,the fixed volume of the cassette would inevitably mean a loss of tapelength.

The present invention is not subject to any significant limitations inregard to the binders used for bonding the interlayer. The binders usedin version a1) may be the same as those used in the formation of thewhite-pigmented transfer layer. Version a2) may even use those bindersor polymers which are part of the layer of pressure-sensitive adhesive.Reference is made in this connection to the foregoing observations.

The auxiliary support of the transfer tape according to the inventionpreferably consists of a plastic film of the type normally used for thesupports of typewriter ribbons, for example of polyethyleneterephthalate, polypropylene, polyethylene, polyvinyl chloride orpolycarbonate. Silicone-coated paper has also proved to be a suitableauxiliary support. The silicone coating leads to a reduction in theadhesive tension between the binder-containing transfer layer and theauxiliary support. It may be replaced by other non-stick materials, forexample by polytetrafluoroethylene.

The auxiliary support is preferably about 10 to 16 μm thick and, morepreferably, about 15 to 55 μm thick.

The above-described materials of the individual layers of the transfertape according to the invention generally satisfy the basic requirementthat, in the case of version a), the lowest adhesive tension (definedvia the adhesion energy in accordance with Dupre's equation, Lit.: K. L.Wolf “Physik und Chemie der Grenzflächen”, Springer Verlag 1957, page164) occurring in the transfer layer/interlayer/pressure-sensitiveadhesive layer combination or, in the case of version b), the adhesivetension between the transfer layer and the layer of pressure-sensitiveadhesive is greater than the adhesive tension occurring between theauxiliary support and the transfer layer. If this is not the case, asuitable non-stick layer would have to be applied to the auxiliarysupport to satisfy this basic requirement. The transfer layer formed onthe substrate should not be adhesive to other materials coming intocontact with it, i.e. on contact with the hand or with paper. In thefinal analysis, therefore, the following adhesive tension ratios arenecessary for the successful use of the transfer tape according to theinvention, the symbol “S” standing for the adhesive tension ratiobetween the various materials: S₁ paper/pressure-sensitive adhesivelayer, S₂ weakest bond in the transferlayer/interlayer/pressure-sensitive adhesive layer combination, S₃transfer layer/auxiliary support, S₄ transfer layer/paper and S₅pressure-sensitive adhesive layer/(back of the) support. Numerousrequirements have to be satisfied in this regard: S₁ greater than S₃, S₂greater than S₃, S₅ far smaller than S₂ and S₅ smaller than S₃. Inaddition, the free surface of the transfer layer applied to a substrate,more particularly to paper, should not be adhesive on the outside, i.e.S₄ is zero or substantially zero. In addition, where the transfer tapeaccording to the invention is used in the form of a roll in a hand-helddispenser, this ensures that the pressure-sensitive adhesive layer showsan adhesion to the back of the auxiliary support which is weaker thanthe weakest adhesion in the transfer layer/interlayer/pressure-sensitiveadhesive layer combination and weaker than the adhesion between thetransfer layer and the auxiliary layer.

The transfer tape according to the invention is used with advantage indispensers which enable the transfer layer coated with thepressure-sensitive adhesive to be unrolled and, at the same time, theauxiliary support to be rolled up. This leads on the one hand toparticularly easy handling of the transfer tape according to theinvention. Commercial hand-held dispensers may be used. A so-called handroller is particularly suitable for this purpose. In hand rollers, aneasy-grip housing accommodates a feed spool with the transfer tape fromwhich it is guided over an application nib projecting from the housingand, from there, back to a take-up spool in the housing. A suitable gearbetween the two spools in the housing ensures that the transfer tape isalways under sufficient tension. To use the transfer tape, the userpicks up the dispenser and, by means of the application nib, presses the(removable) tape layer passing over its terminal edge onto the substrateto which it is to be transferred (for example a printed sheet of paperto make corrections). While applying pressure, the user moves thedispenser relative to the substrate and, in doing so, transfers forexample an opaque layer or a fluorescent layer to the substrate, theflexible auxiliary support being offwound from the feed spool and woundonto the take-up spool.

In the final analysis, the advantages afforded by the invention lie inparticular in the fact that a significant increase in covering power isachieved with the transfer tape according to the invention without anyof the disadvantages which would arise if the content of darkeningpigments were to be increased in the white-pigmented transfer layer.Even where white-pigmented transfer layers are intentionally toned down,a surprising effect is obtained by adopting the solution proposed inaccordance with the invention. In this case, too, covering powder isunexpectedly increased.

Technologically, the present invention may be explained as follows butis not in any way limited to this explanation. In the prior art citedearlier, the transfer layer is also toned down. The effects obtained maybe explained by the fact that the relatively large white pigmentparticles, more particularly titanium dioxide particles, are separatedfrom one another by sizeable empty spaces which allow light beams topass through to a considerable extent onto the letters to be masked sothat they are not completely covered and show through. The whitepigments in question cannot be produced in significantly smaller sizesat reasonable cost. The situation is different, for example, with carbonblack of which the particles can readily be produced in colloidalparticle sizes. By toning down the white-pigmented transfer layer, therelatively small carbon black particles are arranged in the empty spaceswith the result that the passage of light beams is at least limited.There are limits to any increase in the quantity of carbon black usedbecause the “whiteness” of the white-pigmented transfer layer isimpaired to an increasing extent. Now, it must be extremely surprisingto the expert that, in the absence of the darkening mentioned above,features a) and/or b) of the invention not only enable the desiredwhiteness of the white-pigmented transfer layer to remain substantiallyintact, they also increase the covering power of the transfer layer to asurprisingly favorable extent. This will be readily apparent to theobserver. The possibility of still toning down the transfer layer to aslight extent remains unaffected.

The invention is illustrated by the following Examples:

EXAMPLE 1

The following aqueous dispersion is prepared for forming thewhite-pigmented transfer layer:

Aqueous acrylate dispersion 23.42 parts by weight (25% in water;Worleecryl ® 7712W, a product of Worlee Chemie GmbH, Hamburg) Lactimon ®WS 0.8 part by weight (alkylammonium salts of polycarboxylic acids andpolysiloxane copolymer) 2-Butoxyethanol 1.5 part by weight Byk ®-034 0.2part by weight (hydrophobic silicone-like components in mineral oil)Byk ®-307 0.02 part by weight (polyether-modified dimethyl polysiloxanecopolymer) Sorbitol 5.00 parts by weight Silica 4.00 parts by weightTitanium dioxide 35.00 parts by weight Ivory black 0.06 part by weightAqueous dispersion of fine hollow beads 30.00 parts by weight 100.00parts by weight

The aqueous hollow-bead dispersion mentioned above is prepared asfollows:

800 Parts by weight of Ropaque® Emulsion Op-62 LO-E commerciallyavailable from Rohm & Haas Company, Philadelphia, USA (consisting of anon-film-forming polymer with an effective solids content of 52% and anactual solids content of 37.5% and a pH value of 8.0 to 8.7 (particlediameter 0.4 μm, internal diameter 0.28 μm) are mixed with 176 parts byweight of water and 2 parts by weight of a defoamer (Byk®-034,hydrophobic silicone-containing components in mineral oil) and 22 partsby weight of a formic acid solution (prepared by mixing 100 parts byweight of conc. formic acid and 900 parts by weight of water). 30 Partsby weight of this acidified dispersion are used in the aboveformulation.

The above masking composition is knife-coated onto a siliconized papersupport in a quantity of 18 g/m². The water is then evaporated off atabout 80° C. by passing warm air over the paper support.

An aqueous dispersion consisting of the following components is thenknife-coated onto the surface of the transfer layer.

Water 30.5 parts by weight Colanylschwarz PR 130 0.5 part by weight (aproduct of Hoechst AG, carbon black content about 30%, rest water anddispersant = paste) Polymer dispersion VP 859/6 67.00 parts by weight(50% acrylate pressure-sensitive adhesive, a product of Freihoff) 25%Ammonia 2.00 parts by weight 100.00 parts by weight

EXAMPLE 2

The procedure was as in Example 1 except that the following formulationwas used for the adhesive layer:

Water 28.00 parts by weight Aquasilber Aluminiumpaste LPW/1380 5.00parts by weight (a product of Carl Schlenk AG; aluminium content 65%,water content 35%; particle size 9 μm for an average of 50.3% of theparticles) Lactimon WS 0.50 part by weight Polymer dispersion VP 859/665.00 parts by weight 25% Aqueous ammonia 1.50 part by weight 100.00parts by weight

We claim:
 1. A multilayer flexible transfer tape comprising an auxiliarysupport, a pressure-sensitive adhesive layer about 1 to 5 μm thick, anda binder-containing white-pigmented transfer layer about 15 to 25 μmthick comprised of titanium dioxide having greater adhesion to thepressure-sensitive adhesive layer than to the auxiliary support which ispresent between the auxiliary support ad the pressure-sensitive adhesivelayer, characterized in that from about 0.1 to 5% by weight of anon-white pigment is dispersed in a polymer-bonded interlayer situatedbetween the white-pigmented transfer layer and the pressure-sensitiveadhesive layer.
 2. The transfer tape of claim 1 wherein thepressure-sensitive adhesive layer is comprised of at least 0.1% byweight of a non-white pigment.
 3. The transfer tape of claim 1 whereinthe polymer-bonded interlayer is comprised of about 0.2 to 3.5% byweight of the non-white pigment.
 4. The transfer tape of claim 1 whereinthe pressure-sensitive adhesive layer is comprised of about 0.2 to 3.5%by weight of a non-white pigment.
 5. The transfer tape of claim 1wherein the non-white pigment is a black pigment.
 6. The transfer tapeof claim 5, wherein the black pigment is carbon black.
 7. The transfertape of claim 1 wherein the non-white pigment is aluminum.
 8. Thetransfer tape of claim 1 wherein the polymer-bonded interlayer is about1 to 5 μm thick.
 9. An article of manufacture comprising: the multilayerflexible transfer tape of claim 1 in roll form in a hand-held dispenser.10. A multilayer flexible transfer tape comprising an auxiliary support,a pressure-sensitive adhesive layer about 1 to 5 μm thick, and abinder-containing white-pigmented transfer layer about 15 to 25 μm thickcomprised of titanium dioxide having greater adhesion to thepressure-sensitive adhesive layer than to the auxiliary support which ispresent between the auxiliary support and the pressure-sensitiveadhesive layer, characterized in that from about 0.1 to 5% by weight ofa non-white pigment is present in a polymer-bonded interlayer situatedon the white-pigmented transfer layer.
 11. The transfer tape of claim 10wherein the pressure-sensitive adhesive layer is comprised of at least0.1% by weight of a non-white pigment.
 12. The transfer tape of claim 10wherein the polymer-bonded interlayer comprised of about 0.2 to 3.5% byweight of the non-white pigment.
 13. The transfer tape of claim 10wherein the pressure-sensitive adhesive layer is comprised of about 0.2to 3.5% by weight of a non-white pigment.
 14. The transfer tape of claim10 wherein the non-white pigment is a black pigment.
 15. The transfertape of claim 14 wherein the black pigment is carbon black.
 16. Thetransfer tape of claim 10 wherein the non-white pigment is aluminum. 17.The transfer tape of claim 10 wherein the polymer-bonded interlayer isabout 1 to 5 μm thick.
 18. An article of manufacture comprising: themultilayer flexible transfer tape of claim 10 in roll form in ahand-held dispenser.
 19. A multilayer flexible transfer tape comprisingan auxiliary support, a pressure-sensitive adhesive layer, and abinder-containing white-pigmented transfer layer having a greateradhesion to the pressure-sensitive adhesive layer than to the auxiliarysupport which is present between the auxiliary support and thepressure-sensitive adhesive layer, characterized in that a non-whitepigment is present in a polymer-bonded interlayer situated in thewhite-pigmented transfer layer.
 20. The transfer tape of claim 19wherein the polymer-bonded interlayer is comprised of 0.1 to about 5% byweight of the non-white pigment.
 21. The transfer tape of claim 19wherein the non-white pigment is a black pigment or aluminum.
 22. Thetransfer tape of claim 21 wherein the black pigment is carbon black. 23.The transfer tape of claim 19 wherein the white pigment is selected fromthe group consisting of titanium dioxide, precipitated chalk, aluminaand colloidal silicas.
 24. The transfer tape of claim 19 wherein thepressure-sensitive adhesive layer is about 1 to 5 μm thick, the transferlayer is about 15 to 25 μm thick and the polymer-bonded interlayer isabout 1 to 5 μm thick.